Subject: [Sigtran] Query on DRN usage.

From: [email-masked]
Date: Mon, 5 Dec 2005 13:02:48 +0530

Hi Brian,
              As per RFC  section 3.10.5 , Destination Reference No is
allocated by the SUA instance.
 
Lets take the following scenario,
 Peer ASP has registered DRN  to the SG through ASPAC message.
 CORE message is being  sent ,say from SG to peer ASP,  and it contains
the Source reference No.
 ASP sends an COAK message in return and it contains the Destination
Reference No. in it.
 
Should we take down this connection if the received Destination
Reference No. does not match with the One registered for this Peer in
the SG?
Regards,
Partha.
 
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---

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Mon, 5 Dec 2005 01:29:02 -0700

partha.dey,

[email-masked] wrote:                                     (Mon, 05 Dec 2005 13:02:48)
>     CORE  message  is being   sent  ,say  from  SG  to  peer ASP,  and it
>    contains the Source reference No.
> 

Well, no, not necessarily.  It might be worth informing local management
at the SG, and then it might not.

One ASP could accept a CORE, form a connection, but hand it off to
another ASP through ASP-ASP communication or shared state, and then
reply with a DRN assigned by the ASP to which it is handed off.

DRN Labels are not necessarily symmetric.  It just means that all
messages with those DRNs sent from SG->ASP will be sent to the ASP that
registered the label.   It does not restrict what DRNs an ASP sends to
an SG.  The SG is (err, might be) perfectly capable of routing the
message regardless of what DRN it contains.

In the typical case, one would expect that the DRNs sent by an ASP would
be in the DRN label range for which they registered, but there are other
possibilities.  It might be worth (providing an option) informing local
management at the SG on a 1st-and-delta basis if this occurs.

--brian

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/